The stitched writer has been the major workhorse of the data recording industry for the past several years due to its capability to provide narrow track width as well as for its tolerance control. On the other hand, the planar writer has proven to have better mechanical behavior due to its planar and non-recessed structure. Both writer designs can, however, be further improved by adopting aggressive stitching techniques to overcome the following problems.
A. FIG. 1 illustrates a LDCR (low DC resistance) write head which is an example of a stitched writer design. Seen there are shielding layers 11 and 12 (11 being part of the reader head which is not shown), lower pole 13 (P1) and stitched pole 16 (P2). Also shown are coils 14, insulation 17, and upper pole 15 (P3). Not shown, but necessarily present, is a write gap between 15 and 16. The recession of P3, 15, relative to P2, 16, can impact over-writing, write saturation, and adjacent track erasure. With smaller track width, one can further enhance the writing capability and write saturation by reducing the recession and by ensuring balanced adjacent track erasure. However, the integrity of the alumina that is used to fill in the P3 recession area (element 18) turns out to be a problem due to poor step coverage by the alumina.
B. FIG. 2 illustrates an example of a planar writer. Seen there are shielding layers 11, 12, and 13 (11 being part of the reader head which is not shown). Lower pole P1 is made up of three parts, 24, 25, and 26 while P2 is upper pole 15. Also shown are coils 14 and insulation 17. As noted above, not shown, but necessarily present, is a write gap between 15 and 26. For this type of design, ATE (adjacent track erasure) is a serious problem. Either the P2 flank field or the P1 field induces the ATE problem. A reduction of the P2 flank field can be achieved by using a P2 step design, as show, but to further reduce the P1 field induced by the PPT (perpendicular pole trim) process, one needs to either recess a portion of P1 or further extend P1 to enhance the P1/P2 coupling. However, having a recessed P1 portion gives rise to the same alumina integrity problem discussed above, i.e. the poor alumina step coverage associated with element 28.
The present invention discloses how to overcome the alumina integrity problem at the ABS (air bearing surface). The invention makes possible both aggressive P3 stitching as well as aggressive P1 recession without any of the problems associated with the alumina integrity.
A routine search of the prior art was performed with the following references of interest being found:
In U.S. Pat. No. 6,608,737, a Headway patent, Han et al. show a plated P2 where Ps is stitched to P2. In U.S. Pat. No. 6,591,480, Chen et al. disclose forming both poles by plating where an upper pole yoke is plated over the upper pole piece.